A master cylinder used in a vehicular brake apparatus is provided with a first hydraulic pressure chamber in which a hydraulic pressure is generated in response to the operation of a brake operating member and a second hydraulic pressure chamber where the hydraulic pressure therein increases or decreases mechanically responding to the operation of the brake operating member and the hydraulic pressure acts on the brake operating member by a force of the hydraulic pressure. The feeling generated upon depression of the brake operating member by an operator of the vehicle (for example, how the operator feels upon depression of a brake pedal) is influenced by the hydraulic pressure in the second hydraulic pressure chamber. Such vehicular brake apparatus is disclosed in for example, Japanese patent document 2013-209073 A.